Factor RPC request mechanism out of RpcClient into *RpcClientRequest

client/src/generic_rpc_client_request.rs

@@ -0,0 +1,10 @@
+use crate::rpc_request::RpcRequest;
+
+pub(crate) trait GenericRpcClientRequest {
+    fn send(
+        &self,
+        request: &RpcRequest,
+        params: Option<serde_json::Value>,
+        retries: usize,
+    ) -> Result<serde_json::Value, Box<dyn std::error::Error>>;
+}